The Moon will be prominent in the evening sky, setting around midnight.

From Ashburn (click to change), it
will become visible at around 17:23 (EST) as the dusk sky fades, 63° above your southern horizon. It will then reach its highest point in the sky at 17:53, 64° above your southern horizon. It will continue to be observable until around 23:54, when it sinks to 7° above your western horizon.

At this time in its monthly cycle of phases, it appears almost exactly half illuminated.

Observing the Moon at first quarter

The Moon orbits the
Earth once every four weeks, causing its phases to cycle through new
moon, first quarter, full moon, last quarter, and back to new moon once
every 29.5 days.

As it progresses through this cycle, it is visible at different times of day.
At last quarter, it rises at around midnight, appears high in the sky by dawn,
and sets at around midday. Click
here for more information about the Moon's
phases.

The period when the Moon shows half phase is ideal for observing the Moon with
a pair of binoculars or a small telescope. The border between the light and
dark portions of the Moon's disk is the best place to look for detail on its
surface, because along this line, the Moon's surface is illuminated at a very
shallow angle. As a result, mountains and crater rims cast long shadows which
are very easy to see. An observer on the Moon would see the Sun on the horizon,
casting long shadows just like the ones we see on Earth at sunrise and sunset.

At first quarter and last quarter, when the terminator line is down the middle
of the Moon, it is best presented for view, without any foreshortening.

Seasonal variation

Although the Moon passes first quarter every month, it is more favourably
placed in the early evening sky at some times of year than others.

It appears high up in the evening sky around the spring equinox,
but much lower towards the horizon around the autumn equinox.

This is because it always lies close to a line across the sky called the
ecliptic. This marks the flat plane in space in which all of the
planets circle the Sun. It is the line through the zodiacal constellations that the Sun
follows through the year.

The altitude at which the Moon appears above the horizon at sunset depends how
steeply the line of the ecliptic is inclined to the horizon. If the plane of
the ecliptic meet the horizon at a very shallow angle, the Moon will rise or
set along a line which is almost parallel to the horizon, and a large
separation from the Sun along this line would still only correspond to a very
low altitude in the sky.

The inclination of the ecliptic plane to the horizon at Ashburn varies between 74° (sunset at the spring equinox) and 27° (sunset at the autumn equinox). On January 12, the ecliptic is inclined at 56° to the western sunset horizon, as shown by the yellow line in the planetarium view above, meaning that on this occasion the Moon is very favourably placed for viewing from Ashburn.

The Moon's position

At the moment it reaches first quarter, the Moon's distance from the Earth will be 401,000 km. Its exact position will be as follows:

Source

The circumstances of this event were computed using the DE405 planetary ephemeris published by the Jet Propulsion Laboratory (JPL).

This event was automatically generated by searching the ephemeris for planetary alignments which are of interest to amateur astronomers, and the text above was generated based on an estimate of your location.